I did not know who the man was until Sal reveals it in the story. I think Phoebe's mother is a bit afraid that a strange man came top the door. I don't think she suspected it was her son.
One possible themes in Chapter 34 is that of perceptions. While waiting for the geyser to blow, everyone anticipates the experience in a different way. Most bystanders back away... Gram inserts herself into the experience... she revels in every...
In context, we learn that some things were acceptable in an emergency... that people were more understanding, that people were given the benefit of the doubt, and that arrest was not the immediate response for a perceived wrongdoing.
Walk Two Moons study guide contains a biography of Sharon Creech, literature essays, quiz questions, major themes, characters, and a full summary and analysis.